Transcript Document
T-111.550 Multimedia Seminar Carlos Herrero 55828H Osmo Tolvanen 46958L What is MBMS and why Multicast/Broadcast is introduced to UMTS MBMS Standarisation in 3GPP Reference architecture model Functional entities to support MBMS MBMS service provisioning: broadcast vs. multicast MBMS Main open issues Conclusions and possible service solutions • Multimedia Broadcast/Multimedia Service • Aims to offer an efficient way to transmit data from single source to multiple destinations over radio network Network resources are saved • MBMS is realised by addition of existing and new functional entities of the 3GPP architecture • For some applications multiple users can receive the same data in the same time: It would benefical for the network to transmit the data only once over a particular link. • Cell Broacast Services (CBS) can be used to transmit low bitrate data to particular cells (service areas). • IP multicast as such can not provide means for multiple subscribers to share radio or core network resources in UMTS system. • “With incresing use of high bandwidth applications in UMTS, especially with large number of users receiving the same high data rate services, efficient informantion distribution is essential. Thus broadcast and multicast are techniques to decrease the amount of data within the network and use the resources more efficiently.” 3GPP TS 22.146 What is 3GPP? • 3rd Generation Partnership Project • Established in 1998 • A collaboration agreement between numerous telecommunication standardisation bodies • Aims to maintain and develop GSM and 3rd Generation Mobile Systems by providing Technical Specifications (TSGs) Technical specifications (TSGs) for MBMS • TSG 22: TS 22.146 ”Requirements for MBMS” • TSG 23: TS 23.246 “Architecture and functional description” • TSG 25: TS 25.446 “UTRAN Interface Aspects” • TSG 26: TS 26.346 “Codecs and Protocols” • TSG 29: TS 29.846 “Procedure Description” Content Provider CBC PDN (e.g. Internet) OSA SCS HLR CSE Content Provider BM-SC Gmb Gr Gi Uu UE Iu UTRAN Gn/Gp SGSN Gi GGSN Gi BG Gi Iu/Gb Um UE GERAN Multicast Broadcast Source Multicast Broadcast Source Minimum number of changes to existing infrastructure User Equipment: UE Radio Access Network: UTRAN/GERAN Serving GPRS Support Node (SGSN ) Gateway GPRS Support Node (GGSN) Broadcast-Multicast Service Centre: BM-SC Content Provider CBC User Equipment PDN (e.g. Internet) OSA SCS HLR CSE Content Provider BM-SC Gmb Gr Gi Uu UE Iu UTRAN Gn/Gp SGSN Gi GGSN Gi BG Gi Iu/Gb Um UE GERAN Multicast Broadcast Source Multicast Broadcast Source Content Provider CBC Radio Access Network PDN (e.g. Internet) OSA SCS HLR CSE Content Provider BM-SC Gmb Gr Gi Uu UE Iu UTRAN Gn/Gp SGSN Gi GGSN Gi BG Gi Iu/Gb Um UE GERAN Multicast Broadcast Source Multicast Broadcast Source Serving GPRS Support Node Content Provider CBC PDN (e.g. Internet) OSA SCS HLR CSE Content Provider BM-SC Gmb Gr Gi Uu UE Iu UTRAN Gn/Gp SGSN Gi GGSN Gi BG Gi Iu/Gb Um UE GERAN Multicast Broadcast Source Multicast Broadcast Source Content Provider CBC Gateway GPRS Support Node PDN (e.g. Internet) OSA SCS HLR CSE Content Provider BM-SC Gmb Gr Gi Uu UE Iu UTRAN Gn/Gp SGSN Gi GGSN Gi BG Gi Iu/Gb Um UE GERAN Multicast Broadcast Source Multicast Broadcast Source Broadcast/ Multicast Service Centre Content Provider CBC PDN (e.g. Internet) OSA SCS HLR CSE Content Provider BM-SC Gmb Gr Gi Uu UE Iu UTRAN Gn/Gp SGSN Gi GGSN Gi BG Gi Iu/Gb Um UE GERAN Multicast Broadcast Source Multicast Broadcast Source • MBMS functions in two modes: The Broadcast Mode * available without subscription for all UEs in a cell The Multicast Mode * requires subscription The connection procedure The multicast mode Subscription The broadcast mode Service announcement Service announcement Joining Session start Session Start MBMS notification MBMS notification Data transfer Data transfer Session Stop Leaving Session Stop Service announcement • Operator may use different mechanisms to inform users about available MBMS services (service discovery) • Announcements are available also for those who are not subscribed • Location information may be used Service announcement Session Start MBMS notification Data transfer Session Stop Session start (network set up) • Establishes the needed network resources for the MBMS data transfer • Resources are reserved from both core network and radio access network Service announcement Session Start MBMS notification Data transfer Session Stop MBMS notification • Informs users about on-going or fothcoming services • available for all users with activated MBMS services Service announcement Session Start MBMS notification Data transfer Session Stop Data transfer • The data is transferred to the user equipments (UEs) • The UE is in connected mode • No ciphering • No retransmitting, so there may be some data loss Service announcement Session Start MBMS notification Data transfer Session Stop Session stop • The reserved network resources are released when there’s no more data to be transferred Service announcement Session Start MBMS notification Data transfer Session Stop Subscription Subscription • First the user starts a relationship with the operator by subscribing to a spesific MBMS service Service announcement • After subscription the user may receive related MBMS service and operator may charge for it Session Stop • Subscription can be made for example in the internet Joining Session start MBMS notification Data transfer Leaving Service announcement Subscription • Same as in broadcast mode Service announcement Joining Session start MBMS notification Data transfer Session Stop Leaving Joining Subscription • In the joining phase the user indicates to the network that he/she wants to specific multicast data stream • Joining can be made at any time • Used for charging so authentication is needed Service announcement Joining Session start MBMS notification Data transfer Session Stop Leaving Session start Subscription • Same as in broadcast mode with one exception: • The network decides whether a common channel for all UEs in a cell is used, or separate channel for each UE Service announcement Joining Session start MBMS notification Data transfer Session Stop Leaving MBMS notification • Same as in the broadcast mode Data transfer • Data is encrypted • Otherwise same as in the broadcast mode Session stop • Same as in the broadcast mode Subscription Service announcement Joining Session start MBMS notification Data transfer Session Stop Leaving Leaving Subscription • When user no longer wants to belong to a multicast group and receive data transfer • Doesn’t unsubscribe the user from the service, just from the current data transfer • Can be made any time Service announcement Joining Session start MBMS notification Data transfer Session Stop Leaving • Security: Network level or application level ciphering • MBMS Service Area. • System requirements at User Equipment. • Codecs and protocols. • Mobility of user equipment • IP multicast traffic can be received by mobile subcscribers already: However, IP multicast is transparent to UMTS system and ptp connection between each UE and GGSN is used. • MBMS is transparent to end users (they have same experience as with ptp connections) but saves resources on the mobile operator side: optimization of the radio access • For example in a sports event, playbacks can be broadcasted to all audience UEs automatically • Operators can use MBMS to inform about new services